1. Field of the Invention
The present invention relates to a medical image processing method of superposing character data or image data into image data obtained by radiography, and a medical image processing apparatus using the medical image processing method.
2. Description of a Related Art
Photography using radiation (X-ray, α-ray, β-ray, γ-ray, electron beam, ultraviolet ray and so on) is conventionally utilized in various fields, and is one of most important means for a diagnosis particularly in a medical field. An X-ray radiography is variously improved since the realization of a first X-ray radiograph, and a method using combination of a fluorescent screen and an X-ray film is a main current at present. In recent years, various digitalized devices such as an X-ray CT, an ultrasonic diagnosis and an MRI are practically used in a medical image diagnosis, and construction of diagnostic information processing systems, etc. within hospitals is going to be advanced. Many researches for the digitalization have been also made with respect to an X-ray image, and radiography using a photostimulable phosphor is established and is practically used as a method to replace the conventional X-ray radiography.
Photostimulable phosphor (accumulating phosphor) is such substance that accumulates a part of radiation energy when irradiated with radiation and then generates photostimulated luminescence light in accordance with the accumulated energy when irradiated with excitation light such as a visible ray. Existence of the photostimulable phosphor was conventionally known. Radiography using the photostimulable phosphor is constructed as follows. That is, a radiation image of an object such as a human body is photographed and recorded on a sheet coated with the photostimulable phosphor. When the photostimulable phosphor sheet is scanned by excitation light such as a laser beam, photostimulated luminescence light is generated so that image data is obtained by photo-electrically reading the light. After the image data is suitably processed, an image represented by the image data is displayed on a display such as a CRT, or is printed on a film by a laser printer, etc. so that the radiation image can be displayed as a visible image.
Such radiography has performance equivalent to the conventional X-ray radiography in view of photographing sensitivity and image quality. For example, in comparison with the conventional X-ray radiography, an exposure area is very wide and a response of the photostimulated luminescence light to an exposure amount is approximately proportional to the exposure amount over the entire exposure area. Therefore, even when the object is photographed in any radiation amount, a luminescence area where the image exists can be grasped and normalized to be converted into a digital signal without under and over amounts. By combining the obtained signal with a suitable image processing method, an image of high quality can be steadily provided even under various kinds of photographing condition. Further, since the obtained image is stored as image data, a large amount of image data can be stored for a long time period without causing deterioration of the image, and developments to a medical diagnostic information system, etc. can be realized.
In the radiography, only one portion of the photographed object is photographed in many cases. For example, in the case of photographing breasts, the breasts are photographed plural times by changing a photographing direction with respect to each of left-hand and right-hand breasts. As a result, it is impossible to discriminate from which direction the X-ray images are obtained by photographing with respect to which breast when the X-ray images are merely seen at a diagnostic time. Therefore, in the conventional X-ray radiography, a character die formed by lead was taken together with the object into a photograph in order to display photographing condition such as an orientation of a patient or an incident direction of the X-ray at the photographing time within the X-ray image. Namely, the character die such as “R” representing the right and “L” representing the left is taken together with the object into the photograph so that a shadow of the character die is taken on the film. Accordingly, a diagnostician can easily discriminate a photographed portion, a photographing direction and so on. The character photographed in the X-ray image is called as a lead character.
In the radiography system for medicine using the photostimulable phosphor, character data or image data relative to photographing information and corresponding to the lead character as mentioned above is superposed into a digital image after image generation. However, according to the conventional method, work for superposing the data must be manually made every time. Therefore, when the data is often superposed, the efficiency is very low. Further, only the character data or the image data determined in advance can be superposed by such a way. Therefore, there was also a case where required character data was not prepared in some apparatuses.